Method and apparatus for electrically forming pipe



s. WESTIN 2, METHOD AND APPARATUS FOR ELECTRICALLY FORMING PIPE May 1, 1945.

Filed Oct. 30, 1942 Sven Wesfin INVENTOR. KM

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Ill rlllllllllllllllllll! ATTORNEY.

Patented Mayv l, 1945 OFFICE Mn'mon AND APPARATUS Fo'R ELEC- TRICALLY F Sven Westin, West Allis, Wis.,

ORMING PIPE assignor to A. 0.

Smith Corporation, Milwaukee, Wis., a corporation of New York Application October 30, 1942, Serial No. 463,957

3 Claims. (01. 219-3) This invention relates to method and apparatus for electrically forming pipe.

In employing the process set forth and claimed in the copending application of the present inventor and Axel Westin, Serial No. 376,669, filed January 30, 1941, for Method of treating metallic bodies, now Patent No. 2,309,561, dated January 26, 1943, in the reduction of pipe in diameter, a number of difllculties Such difliculties arise largely due to the requirement of applyingtorque to the blank along with a longitudinal pressure.

The object of the invention is to obtain a substantial reduction in diameter of a pipe section in one operation and without involving waste at the end and without securing successive pipe sections end to end.

Another object is and economic method pipe.

In carrying out the invention, a section of pipe is treated first at one end to reduceits diameter for a substantial length, and then it is removed from the treating machine and the remainder of the blank treated by progressive action from the other end, either in a separate machine or by reversal end to end of the blank and reinsertion in the same machine. For this purpose, the forming machine is constructed with its dies radially movable to provide for separation of the same in releasing the partially formed blank therefrom.

The accompanying drawing illustrates an embodiment of the invention and the practice of the method referred to.

In the drawing:

Figure 1 is a diagrammatic elevational view partly in section of apparatus embodying the invention and showing the blank in position for treatment;

Fig. 2 is a view similar to Fig. 1 showing the blank partially formed and the dies separated preparatory to removal of the blank; and

Fig. 3 is a similar view showing the blank turned end for end and reinserted in the apparatus.

The apparatus'comprises in general a feeding to provide a more simple and apparatus for reducing apparatus and a forming apparatus.

The feeding apparatus comprises a rotary chuck I mounted on a longitudinally slidable pedestal 2 and rotated by a motor 3 and reduction gearing 4 also carried by the pedestal. A hydraullic cylinder 5 is disposed to push the tudinally toward the forming apparatus.

The forming apparatus comprises two or more pedestal 2 longihave been encountered.

electrode dies 6 and I, opposed to each other radially and having their die surfaces tapered to provide a conical die cavity 8 with a circular opening at the small end through which the reduced pipe is discharged.

The dies 6 and 1 are mounted for radial movement toward and away from each other under the control of hydraulic cylinders 9 or some mechanical power mechanism. The dies are held in spaced relation during forming operations as indicated in Fig. l.

The dies 6 and l constitute electrodes for supplying electricity to the blank as the latter rotates in contact with them. For this purpose leads I0 connect the dies to the secondary of a transformer II. Leads l2 connect the primary of the transformer II to a source of electric currentd3.

In operation, the pipe blank I4 is gripped at one end by the chuck I, the other end of the blank extending toward the large open end of the die cavity 8. The chuck I is then rotated and fed toward the forming apparatus to causethe free end of,the blank to enter the die cavity 8 and engage the tapered faces of the dies 6 and 1. The electricity being supplied to the dies passes through the portions of the blank between the die electrodes and heats a circumferential portion of the end of the blank.

Heating of the blank at the end softens it and allows it to yield to the radial pressure of the dies under the longitudinal pressure of the feeding movement. This brings more of the blank into contact with the dies and the end of the blank progressively moves forward and is contracted in the die cavity until it is reduced to the diameter of the exit opening where it is progressively discharged from the forming apparatus.

After a substantial length of the blank I4 has been reduced as described, the electricity is shut off and the forming operations stopped by separating dies 6 and I by means of the cylinders 9. Then the chuck I and blank I4 are retracted from the forming apparatus.

The partially reduced blank is turned end for end, as illustrated in Fig. 3, and its small end is then gripped by chuck I. The large end is then fed through the dies in the same manner as described for the previous forming operation, with the dies brought into operating position, the current turned on, the chuck I rotating and the cylinder 5 feeding the blank forward. In this latter forming operation the reduction of the blank is ordinarily completed so that the finished blank is or the same reduced diameter throughout its length.

If it is desired to have an enlarged portion of the blank remain in the finished product, the forming operation can be stopped at the right location to leave such a portion. the blank being reduced from opposite ends to such location.

Various embodiments of the invention may be employed within the scope or the accompanying claims.

I claim:

1. The method of reducing pipe and the like to uniform diameter and wall thickness without waste at the ends, comprising simultaneously electrically heating and forming the blank by pushing' the same through an electrode die first progressively from one end toward the middle and then from the other end to the location of the first forming.

2. The method of reducing a cylindrical structure for a portion of its length beginning at one end, comprising feeding the same through a restricted die opening constituted 01 a plurality of spaced die electrodes supplying heating current to the blank while the electrodes and blank are relatively rotated to effect reduction of the blank in diameter as it progresses through the die, and stopping the forming operations and separating the electrode dies at the location where the reduction is to. end.

3. The method or reducing a cylindrical blank in diameter, comprising pushing the same through a restricted die opening constituted of,

a, plurality of spaced die electrodes supplying heating'current to the blank while the electrodes and blank are relatively rotated to effect a progressive'reduction of the blank from one end toward the other, stopping the forming operations before the blank is completely fed through the die, and releasing the blank from the electrodes, and thereafter similarly reducing the blank from its opposite end. 

